Link Layer Protocol and Error Correction

What is the primary function of the link layer in the network stack?

What is the purpose of the EDC (Error Detection and Correction) bits?

What is the main difference between half-duplex and full-duplex communication?

What is the purpose of the Internet checksum?

What is the name of the protocol that uses a 32-bit checksum to detect errors in transmitted segments?

Where is the link layer typically implemented in a network node?

What is the purpose of the Data Link Layer in a network?

What type of addressing is used in the Data Link Layer?

What is the purpose of framing in the Data Link Layer?

What is the primary function of the Data Link Layer in relation to error handling?

What is the purpose of flow control in the Data Link Layer?

What is the relationship between the Data Link Layer and the Transport Layer in terms of reliable delivery?

What is the primary purpose of a MAC address?

What is the significance of the IEEE in MAC address allocation?

What is the advantage of a MAC address being flat?

What is the function of ARP in LAN technologies?

What is the size of a typical MAC address in LAN technologies?

What is the purpose of error detection and correction in LAN technologies?

The data link layer is responsible for transferring datagrams from one node to an adjacent node over a link.
The layer's services include framing, link access, reliable delivery, flow control, and error detection.

Error detection involves adding error checking bits (redundancy) to data to detect errors.
Error correction involves identifying and correcting bit errors without resorting to retransmission.
Error detection is not 100% reliable, and protocols may miss some errors.

The internet checksum is used to detect errors in transmitted segments at the transport layer.
The sender computes the checksum by adding the segment contents as 16-bit integers and storing the value in the UDP checksum field.
The receiver checks if the computed checksum equals the checksum field value; if not, an error is detected.

Framing involves encapsulating datagrams into frames, adding headers and trailers.
Link access controls channel access if shared medium.
'Physical addresses' (MAC addresses) are used in frame headers to identify source and destination nodes.

Reliable delivery between adjacent nodes involves ensuring that data is delivered correctly and in the correct order.

Flow control involves pacing between adjacent sending and receiving nodes to prevent data overflow.

LAN technologies include Ethernet, hubs, bridges, switches, 802.11, PPP, and ATM.
The data link layer is responsible for addressing in LANs.

LAN addresses (MAC addresses) are used to get datagrams from one interface to another physically-connected interface.
32-bit IP addresses are used to get datagrams to destination IP networks.
LAN addresses are 48-bit addresses burned in the adapter ROM.
MAC addresses are allocated by the IEEE to ensure uniqueness.